If you want to run the rear height the same, on option is to get a SINGLE lift block (of whatever height you want). The factory one has the bumpstop, but non 4x4 trucks don't use that. The bumpstop for them just sticks down from the frame and (presumably) contacts the axle tube, before anything bad happens. If you can't find a lift block with the height you want and an integral bumpstop, then you likely can get away without running a bumpstop at all, if you don't routinely carry a ton in the back, or jump the truck off-road.
The advice to get NEW u-bolts (doesn't matter who they are from) is because the u-bolts can stretch, fatigue, etc. Not knowing any better I re-used the originals when I lifted my truck, but it's been so long and they've pretty well rusted beyond the point that they could vibrate loose, so I'm not gonna mess with them.